Obama leads tributes to Mandela at memorial service

US President Barack Obama has led the tributes to Nelson Mandela saying that South Africa's democracy is his "cherished legacy." Thousands gathered in Johannesburg to celebrate the life of the former South African president.

In response to the historic handshake between Barack Obama and Cuban president Raul Castro, the US National Security Council has said: "This wasn't a pre-planned encounter. Above all else, today is about honouring Nelson Mandela and that was the President's singular focus at the memorial service.

"We appreciate that people from all over the world are participating in this ceremony."